Digital display systems, such as liquid crystal display (LCD) monitors and televisions, typically receive analog signals from a video source arid convert the analog signals into a digital image. One problem associated with LCD monitors is motion blur, which is the visible distortion of a moving image displayed by the monitor. Motion blur is caused by the relatively slow response time of the liquid crystal elements that make up LCD monitors and the sample and hold characteristic of LCD technology.
Manufacturers have implemented various methods to reduce the motion blur problem. Current methods utilize a double scan approach. In a double scan LCD monitor, the frequency of input video (e.g., N (for example, 50/60 Hz video) is doubled (e.g., converted to N*2 (for example, 100/120 Hz) on the LCD monitor. How to convert the input at frequency N to output at frequency N*2 is thus a challenge for the video controller. One method uses motion estimation and motion compensation (MEMC) to predict where an object will be located in an intermediate frame. Particularly, based on the direction of motion, MEMC will predict object location and generate the intermediate frame as an interpolated frame with the moving object located in the predicted location. FIG. 1 illustrates how this method operates in conjunction with an N (e.g., 50/60) Hz input sequence of frames A, B, C, D . . . , and an N*2 (e.g., 100/120) Hz sequence of output frames. In this example, the output sequence would be A, A′, B, B′, C, C′, D, D′ . . . . The frames A, B, C and D represent the digitized input frames. The frames A′, B′, C′ and D′ represent the interpolated frames, which may include moving objects positioned in locations predicted using MEMC. Because the algorithms required for interpolation using MEMC are relatively complex, this method demands a substantial amount of processing resources to operate correctly. Furthermore, MEMC does not always provide an accurate prediction of object location and thus, there are many cases where MEMC will fail. If the MEMC fails, artifacts may be generated on the output frame, resulting in annoying noise for the viewer. Moreover, MEMC requires a significant amount of logic and memory to implement, and is very expensive.
Another method used to reduce motion blur inserts frames between active frames. The black frames act similar to shutter elements to reduce motion blur effects on the viewer. Particularly, the black screens serve to substantially eliminate or reduce the visual overlap that would otherwise be caused by the sample and hold feature of LCD monitors. FIG. 2 illustrates how this method operates in conjunction with an N (e.g., 50/60) Hz input sequence of frames A, B, C, D . . . , and an N*2 (e.g., 100/120) Hz sequence of output frames. In this example, the output sequence would be A, X, B, X, C, X, D, X . . . , where X represents a black frame. One drawback with this method is that the overall brightness of the display may be adversely affected.
Therefore, it would be desirable to provide an improved system and method for frame insertion within a digital display system that reduces motion blur.